This invention relates to a protective jacket for a disk-shaped recording medium, in particular a flexible data recording medium, comprising a blank of plastics material having openings therein, the blank being folded and joined together at at least two outer edges to form either a closed jacket or a jacket open along at most one edge, and a fleece covering attached to the blank by thermo-welding by means of needles producing needle weld points.
Such known protective jackets of the kind referred to for audio, video and data recording disks, films, X-ray plates, etc. are generally in the form of flat, square or reactangular envelope-like jackets. Regardless of the recording material which has been used in the particular recording medium, which may be capable of storing magnetic, optical or other signals, it is desirable to keep the recording medium free from dirt, dust, etc., in order to minimise the detrimental effect of such matter on the playback quality of the recorded signals. The danger of penetration of dust, etc. is even greater when the recording medium is removed from the jacket than in the case of a FlexyDisk.RTM., in which the recording medium, in the form of a magnetic film, is completely enclosed by the jacket except for a few openings, and also remains enclosed during the recording/playback operation. FNT .RTM. Registered trademark of BASF Aktiengesellschaft
FlexyDisk jackets are produced, for example, from a blank of thin rigid PVC film. Before being folded into a jacket-like form, the side which is later to be the inside of the jacket is provided with a liner made of nonwoven fabric, hereinafter also referred to as "fleece" or "fleece covering". The blank is punched to provide jacket openings. The blank is then folded to form a jacket and the side tabs, which project when the folding operation has been carried out, are folded over and welded to the sides of the jacket. A disk-shaped flexible carrier coated with magnetic dispersion is then inserted into the jacket, which is still open at one edge, after which an end tab of the jacket is folded and welded to the top edge of the jacket so that the magnetic film is thus protected and fully enclosed on all sides. The magnetic film remains inside the jacket when used in a FlexyDisk drive for recording/playback of signals.
German Laid-Open Application DOS No. 3,140,088 discloses a jacket for a magnetic film which is provided on the inside, on both sides of the magnetic film, with linings of a plastic fibre material. This lining material is spot welded to the jacket with some or all of the weld points arranged radially with respect to the magnetic film to provide a sinusoidal cross-sectional contour, across which the magnetic film constantly passes during rotation to effect a thorough cleaning. Mounting the cleaning linings at pre-determined points entails a certain amount of expense in terms of apparatus and control in the production of the jacket.
German Laid-Open Application DOS No. 2,912,064 discloses another jacket for FlexyDisks which possesses buffing material consisting of fleece on the inner surfaces on both sides of the magnetic film. The buffing material is attached to the jacket material via adhesive bonds, either along straight or circular lines. Apart from the potential damage to the recording medium caused by the adhesive, another disadvantage found is that, in relation to the jacket, the points of attachment are lower than the intermediate areas, so that substantial, harmful friction occurs during rotation of the magnetic film and may cause scraping of the film and hence also damage to the magnetic surface.